U.S. patent application number 11/665221 was filed with the patent office on 2008-03-20 for gas barrier resin composition and gas barrier film.
This patent application is currently assigned to TORY INDUSTRIES, INC.. Invention is credited to Takashi Arai, Kusato Hirota, Yasushi Tateishi.
Application Number | 20080070043 11/665221 |
Document ID | / |
Family ID | 36148260 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080070043 |
Kind Code |
A1 |
Arai; Takashi ; et
al. |
March 20, 2008 |
Gas Barrier Resin Composition and Gas Barrier Film
Abstract
Disclosed herein are a gas barrier resin composition which is
free from halogen and which has excellent gas barrier properties,
and a gas barrier film. The gas barrier resin composition includes:
a polymer (A) whose repeating unit contains a functional group with
active hydrogen and/or a polar functional group with hetero atom;
and an organic compound (B) containing, in its molecule, a
functional group with active hydrogen and/or a polar functional
group with hetero atom. The gas barrier film includes the gas
barrier resin composition.
Inventors: |
Arai; Takashi; (Otsu-shi,
JP) ; Tateishi; Yasushi; (Mishima-shi, JP) ;
Hirota; Kusato; (Otsu-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
TORY INDUSTRIES, INC.
1-1, Nihonbashi - Muromachi 2 - chome
Chuo - ku, Tokyo
JP
103-8666
|
Family ID: |
36148260 |
Appl. No.: |
11/665221 |
Filed: |
October 5, 2005 |
PCT Filed: |
October 5, 2005 |
PCT NO: |
PCT/JP05/18408 |
371 Date: |
July 12, 2007 |
Current U.S.
Class: |
428/425.8 ;
428/425.9; 524/1; 524/186; 524/394 |
Current CPC
Class: |
B32B 2307/412 20130101;
B32B 2439/70 20130101; Y10T 428/31605 20150401; C08G 18/12
20130101; C09J 175/12 20130101; B32B 27/40 20130101; C08G 18/0866
20130101; C08G 18/3271 20130101; Y10T 428/31609 20150401; C08G
18/757 20130101; C09D 175/12 20130101; B32B 2307/7242 20130101;
B32B 27/18 20130101; C08G 18/12 20130101; B32B 27/08 20130101; B32B
2255/10 20130101; C08G 18/7642 20130101; B32B 2255/205 20130101;
C08G 18/0823 20130101; C08G 18/3206 20130101 |
Class at
Publication: |
428/425.8 ;
428/425.9; 524/001; 524/186; 524/394 |
International
Class: |
B32B 27/40 20060101
B32B027/40; C08K 5/04 20060101 C08K005/04; C08K 5/17 20060101
C08K005/17 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2004 |
JP |
2004-297302 |
Claims
1. A gas barrier resin composition comprising: a polymer (A) whose
repeating unit contains a functional group with active hydrogen
and/or a polar functional group with hetero atom; and an organic
compound (B) containing, in its molecule, a functional group with
active hydrogen and/or a polar functional group with hetero
atom.
2. The gas barrier resin composition according to claim 1, wherein
the functional group with active hydrogen of the polymer (A) is at
least one kind selected from the group consisting of a hydroxyl
group, an amino group, a carboxyl group, and an amide group.
3. The gas barrier resin composition according to claim 1, wherein
the polar functional group with hetero atom of the polymer (A) is
at least one kind selected from the group consisting of a carbonyl
group, a cyano group, an amide group, and a thiocarbonyl group.
4. The gas barrier resin composition according to claim 1, wherein
the polymer (A) contains at least one selected from the group
consisting of a urethane segment and a urea segment.
5. The gas barrier resin composition according to claim 1, wherein
the polymer (A) is polyurethane.
6. The gas barrier resin composition according to claim 1, wherein
the organic compound (B) contains at least one selected from the
group consisting of a primary amino group, a secondary amino group,
and a carbonyl group.
7. The gas barrier resin composition according to claim 1, wherein
the organic compound (B) is at least one urea-based compound
selected from the group consisting of urea, dimethyl urea, and
thiourea.
8. A gas barrier film comprising the gas barrier resin composition
according to claim 1.
9. The gas barrier film according to claim 8, wherein a resin film
comprising the gas barrier resin composition is laminated onto a
base film.
10. The gas barrier film according to claim 9, further comprising
at least one layer laminated on the base film, the layer being
selected from the group consisting of a metal layer, a metal oxide
layer, and a metal nitride layer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a gas barrier resin
composition which is useful as a film, sheet, or molding material
having excellent oxygen and water vapor barrier properties and
which has excellent base film coating properties, and to a gas
barrier film using such a gas barrier resin composition.
BACKGROUND ART
[0002] Gas barrier films and materials for packaging using the same
are already well known. Among them, aluminum foil is known to have
the most excellent oxygen gas barrier properties, but cannot be
used by itself due to its weak pinhole resistance, except for
special purposes. Therefore, in most cases, aluminum foil is used
as an intermediate layer of a laminated film. Such a laminated film
has excellent gas barrier properties, but is opaque and therefore
there is a drawback that an object wrapped in the laminated film
cannot be seen through the laminated film. In addition, there is
also a drawback that it is difficult to check whether the laminated
film has been properly heat-sealed or not.
[0003] Thermoplastic films such as polyester films and polyamide
films are also used as materials for packaging for a wide range of
purposes due to their high strength, transparency and formability.
However, these thermoplastic films have high permeability to gases
such as oxygen and water vapor, and therefore there is a case where
when such thermoplastic films are used for packaging of common
foods or retort-processed foods, the quality of these foods is
changed or deteriorated during long storage.
[0004] Therefore, in most cases, as materials for packaging
required to have gas barrier properties, such as materials for
packaging food, films obtained by coating base films such as
polyolefin films, nylon films, and polyethylene terephthalate
(hereinafter, abbreviated as "PET") films with an emulsion of
vinylidene chloride (hereinafter, abbreviated as "PVDC") are
conventionally used. Such PVDC-coated films exhibit high oxygen
barrier properties not only under low-humidity conditions but also
under high-humidity conditions, and also exhibit high water vapor
barrier properties. However, when PVDC-coated films are incinerated
in the process of waste disposal, chlorine gas resulting from
chlorine contained in PVDC is generated. In addition, there is also
a fear of generation of dioxin. For this reason, transition from
PVDC-coated films to other materials is strongly desired.
[0005] Polyvinyl alcohol (hereinafter, abbreviated as "PVA") films
and PVA-coated films are the most well-known gas barrier materials
free from chlorine. PVA exhibits excellent oxygen gas barrier
properties in a dry environment. However, the gas barrier
properties of PVA have great dependence on humidity, and are
therefore significantly impaired under high-humidity conditions. In
addition, there is also a problem that PVA does not have water
vapor barrier properties and is easily dissolved in hot water.
[0006] In order to improve gas barrier properties of PVA under
high-humidity conditions, there are proposed a polymer obtained by
mixing PVA and partially neutralized polyacrylic acid or
polymethacrylic acid (see, for example Patent Document 1), a
polymer obtained by mixing PVA, an ethylene-maleic acid copolymer,
and a cross-linking agent (see, for example Patent Document 2), and
a polymer obtained by mixing PVA, polyitaconic acid, and a metal
compound (see Patent Document 3). All these methods are intended to
improve gas barrier properties of a polymer film under
high-humidity conditions by forming a cross-linked structure via
ester bonds. However, in order to improve gas barrier properties of
a polymer film by using such a method, it is necessary to subject
the mixture to reaction by heating it at a high temperature for a
long time to sufficiently proceed esterification, which causes a
problem such as reduction of not only productivity but also
aptitude for after process due to heat shrinkage of a base film, or
deterioration of appearance due to color development.
Patent Document 1: Japanese Patent Application Laid-open No.
H10-237180 (Paragraphs 0060 to 0065)
Patent Document 2: Japanese Patent Laid-open No. 2001-323204
(Paragraphs 0047 to 0058)
Patent Document 3: Japanese Patent Laid-open No. 2004-35833
(Paragraphs 0061 to 0066)
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0007] In view of such background of the prior art, it is an object
of the present invention to provide a gas barrier resin composition
which is free from halogen and which has excellent gas barrier
properties, and a gas barrier film using such a gas barrier resin
composition.
Means for Solving the Problem
[0008] In order to achieve the above object, the present invention
is directed to a gas barrier resin composition including: a polymer
(A) whose repeating unit contains a functional group with active
hydrogen and/or a polar functional group with hetero atom; and an
organic compound (B) containing, in its molecule, a functional
group with active hydrogen and/or a polar functional group with
hetero atom.
[0009] The present invention is also directed to a gas barrier film
including such a gas barrier resin composition.
EFFECT OF THE INVENTION
[0010] According to the present invention, it is possible to
provide a resin composition which has oxygen barrier properties
with little dependence on humidity and high water vapor barrier
properties, and which does not contain halogen such as chlorine. In
addition, the gas barrier resin composition according to the
present invention does not need to be subjected to heat treatment
at a high temperature when formed into a gas barrier layer.
Accordingly, the gas barrier resin composition according to the
present invention is useful as a film, sheet, or molding material,
and has excellent base film coating properties. Further, the use of
such a gas barrier resin composition makes it possible to provide a
gas barrier film which is free from halogen, and which has
excellent gas barrier properties.
BEST MODE FOR CARRYING OUT THE INVENTION
[0011] Intensive studies have been made to achieve the above
object, and as a result, it has been found that a resin composition
including a specific polymer and a specific compound is free from
halogen and exhibits high gas barrier properties and excellent film
forming properties.
[0012] More specifically, the gas barrier resin composition
according to the present invention includes: a polymer (A) whose
repeating unit contains a functional group with active hydrogen
and/or a polar functional group with hetero atom; and an organic
compound (B) containing, in its molecule, a functional group with
active hydrogen and/or a polar functional group with hetero atom,
and has higher gas barrier properties than ever before.
[0013] In the present invention, the functional group with active
hydrogen is at least one kind selected from a hydroxyl group, an
amino group, a carboxyl group, and an amide group, and the polar
functional group with hetero atom is at least one kind selected
from a carbonyl group, a cyano group, an amide group, and a
thiocarbonyl group. Between active hydrogen and the polar
functional group with hetero atom, intermolecular interaction
occurs. Examples of such intermolecular interaction include
hydrogen bonding, electrostatic interaction, hydrophobic
interaction, and Van der Waals force.
[0014] As a factor in determining gas barrier properties of a thin
film layer formed from a resin composition, free volume can be
mentioned. As described-above, since the polymer (A) contains, in
its polymer structure, a functional group allowing intermolecular
interaction such as hydrogen bonding or electrostatic interaction
to occur, molecules of the polymer (A) tend to strongly cohere with
one another by using intermolecular interaction as driving force.
As a result, energy density of cohesion and orientation of the
polymer (A) are increased, thereby reducing free volume. Free
volume serves as a path of gas molecules such as oxygen and water
vapor, and therefore a reduction in free volume improves gas
barrier properties. It can be considered that driving force for
reducing free volume is increased as the density of intermolecular
interaction occurring between molecules of the polymer (A)
increases, thereby increasing the energy density of cohesion of the
polymer (A).
[0015] The organic compound (B) fills remaining free volume which
cannot be reduced by only cohesion between molecules of the polymer
(A). More specifically, the organic compound (B) is inserted
between polymer chains of the polymer (A) to fill free space
between the polymer chains by using intermolecular interaction
occurring between the organic compound (B) and the polymer (A) as
driving force.
[0016] As described above, the present invention is characterized
by improving gas barrier properties by causing intermolecular
interaction between molecules of the polymer (A) and between the
polymer (A) and the organic compound (B). In addition to improved
gas barrier properties, since the organic compound (B) is bonded to
the polymer (A) not via covalent bonding but via intermolecular
interaction, the resin composition according to the present
invention can be formed without using high energy, thereby
significantly improving productivity. The above-mentioned
conventional method using a cross-linking agent involves heating at
a high temperature for a long time to form covalent bonding between
polyvinyl alcohol or the like and a cross-linking agent, whereas
the present invention does not involve heating at a high
temperature for a long time because the polymer (A) and the organic
compound (B) are noncovalently bonded via intermolecular
interaction, thereby significantly improving productivity.
[0017] Hereinbelow, the present invention will be described in
detail.
[0018] The repeating unit of the polymer (A) used in the present
invention may be any one of an aliphatic compound, an alicyclic
compound, and an araliphatic compound, as long as it contains a
functional group with active hydrogen and/or a polar functional
group with hetero atom.
[0019] Examples of the polymer (A) containing a functional group
with active hydrogen and/or a polar functional group with hetero
atom include a polymer containing one selected from the group
consisting of a urethane segment and a urea segment, and a
polyalcohol containing two or more hydroxyl groups.
[0020] The urethane segment or urea segment may be contained in
either a main chain or a side chain of the polymer (A). The
urethane segment and the urea segment are preferred because they
contain, in their structure, both an amino group having active
hydrogen and a carbonyl group which can interact with active
hydrogen, which makes it possible to form a plurality of hydrogen
bonds between molecules of the polymer (A) and between the polymer
(A) and the organic compound (B).
[0021] The urethane segment or urea segment is preferably contained
in a main chain of the polymer (A). This is because the polymer (A)
containing the urethane segment or urea segment in a main chain
thereof is less sterically-bulky than the polymer (A) containing
the urethane segment or urea segment in a side chain thereof, and
therefore there is an advantage that when molecules of the polymer
(A) strongly cohere with one another by using intermolecular
interaction as driving force, free volume can be made smaller.
Among various polymers, polyurethane is preferably used because
polyurethane contains, in its repeating structures, a plurality of
amino groups which can form hydrogen bonding with a polar
functional group with hetero atom and a plurality of carbonyl group
which can form hydrogen bonding with a polar functional group with
active hydrogen, thereby significantly improving gas barrier
properties.
[0022] Such a polyurethahe resin is not particularly limited. For
example, a polyurethane resin obtained by urethanizing reaction of
a diisocyanate component and a diol component can be used. The thus
obtained polyurethane resin may be further subjected to
chain-extending reaction or cross-linking reaction with an amine
component before use.
[0023] Examples of the diisocyanate component include an aromatic
diisocyanate, an araliphatic diisocyanate, an alicyclic
diisocyanate, and an aliphatic diisocyanate.
[0024] Examples of the aromatic diisocyanate include m- or
p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate,
1,5-naphthalene diisocyanate (NDI), 4,4'-, 2,4'-, or
2,2'-diphenylmethane diisocyanate (MDI), 2,4- or 2,6-tolylene
diisocyanate (TDI), and 4,4'-diphenyl ether diisocyanate.
[0025] Examples of the araliphatic diisocyanate include 1,3- or
1,4-xylylene diisocyanate (XDI), and 1,3- or
1,4-tetramethylxylylene diisocyanate (TMXDI).
[0026] Examples of the alicyclic diisocyanate include
1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate,
3-isocyanatemethyl-3,5,5-trimethylcyclohexylisocyanate (isophorone
diisocyanate; IPDI), 4,4'-, 2,4'-, or 2,2'-dicyclohexylmethane
diisocyanate (hydrogenated MDI), methyl-2,4-cyclohexane
diisocyanate, methyl-2,6-cyclohexane diisocyanate, and 1,3- or
1,4-bis(isocyanatemethyl)cyclohexane (hydrogenated XDI).
[0027] Examples of the aliphatic diisocyanate include trimethylene
diisocyanate, tetramethylene diisocyanate, hexamethylene
diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene
diisocyanate, 1,2-, 2,3-, or 1,3-butylene diisocyanate, and 2,4,4-
or 2,2,4-trimethylhexamethylene diisocyanate.
[0028] From the viewpoint of reducing free volume between polymer
chains and reducing steric hindrance upon occurrence of
intermolecular interaction, when the diisocyanate component has a
substituent in its ring, the substituent preferably has a short
chain (e.g., C.sub.1-3 alkyl groups).
[0029] Further, the diisocyanate component preferably has a
symmetric structure. For example, the aromatic diisocyanate is
preferably TDI, MDI, or NDI, the araliphatic diisocyanate is
preferably XDI or TMXDI, the alicyclic diisocyanate is preferably
IPDI, hydrogenated XDI, or hydrogenated MDI, and the aliphatic
diisocyanate is preferably HDI.
[0030] These diisocyanate components can be used singly or in
combination of two or more of them. If necessary, the diisocyanate
component may be used together with a polyisocyanate having three
or more functional groups.
[0031] Examples of the diol component include a wide range of diols
from low-molecular weight diols to oligomers, such as C.sub.2-12
alkylene glycols (e.g., ethylene glycol, 1,3- or 1,2-propylene
glycol, 1,4-, 1,3-, or 1,2-butanediol, 1,5-pentanediol,
3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol,
2,2,4-trimethylpentane-1,3-diol, 1,6-hexanediol, neopentyl glycol,
1,5- or 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol,
1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol); polyether
diols such as polyoxy C.sub.2-4 alkylene glycols (e.g., diethylene
glycol, triethylene glycol, tetraethylene glycol, pentaethylene
glycol, hexaethylene glycol, heptaethylene glycol, dipropylene
glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene
glycol, hexapropylene glycol, heptapropylene glycol, dibutylene
glycol, tributylene glycol, tetrabutylene glycol); aromatic diols
(e.g., bisphenol A, bishydroxyethyl terephthalate, catechol,
resorcin, hydroquinone, 1,3- or 1,4-xylylenediol or a mixture of
them); and alicyclic diols (e.g., hydrogenated bisphenol A,
hydrogenated xylylenediol, cyclohexanediol,
cyclohexanedimethanol).
[0032] Among these diol components, from the viewpoint of gas
barrier properties, C.sub.2-8 diols such as ethylene glycol,
propylene glycol, butanediol, pentanediol, hexanediol, heptanediol,
octanediol, diethylene glycol, triethylene glycol, tetraethylene
glycol, and dipropylene glycol are preferably used, and C.sub.2-6
diols (especially, ethylene glycol, 1,2- or 1,3-propylene glycol,
1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol,
diethylene glycol, triethylene glycol, dipropylene glycol) are more
preferably used.
[0033] These diol components can be used singly or in combination
of two or more of them. If necessary, the diol component may be
used together with a polyol component having three or more
functional groups.
[0034] If necessary, a diamine component may be used as a
chain-extending agent or a cross-linking agent. Examples of such a
diamine component include hydrazine, aliphatic diamines (e.g.,
ethylenediamine, trimethylenediamine, tetramethylenediamine,
pentamethylenediamine, hexamethylenediamine,
2,2,4-trimethylhexamethylenediamine,
2,4,4-trimethylhexamethylenediamine, octamethylenediamine);
aromatic amines (e.g. m- or p-phenylenediamine, 1,3- or
1,4-xylylenediamine or a mixture of them); and alicyclic diamines
(e.g., hydrogenated xylylenediamine, bis(4-aminocyclohexyl)methane,
isophoronediamine, bis(4-amino-3-methylcyclohexyl)methane). In
addition to these diamine components, diamines having a hydroxyl
group, such as 2-hydrazinoethanol and
2-[(2-aminoethyl)amino]ethanol, can also be mentioned. Among these
diamine components, from the viewpoint of gas barrier properties,
low-molecular weight diamine components having 8 or less carbon
atoms are preferably used, and diamine components having 6 or less
carbon atoms (especially, hydrazine, ethylenediamine,
tetramethylenediamine, pentamethylenediamine, hexamethylenediamine,
2-hydrazinoethanol, 2-[(2-aminoethyl)amino]ethanol) are more
preferably used. These diamine components can be used singly or in
combination of two or more of them. If necessary, the diamine
component may be used together with a polyamine component having
three or more functional groups.
[0035] Further, a polyalcohol is preferably used because it has a
plurality of hydroxyl groups, which makes it possible to form a
plurality of hydrogen bonds between molecules of the polymer (A)
and between the polymer (A) and the organic compound (B) Examples
of such a polyalcohol include a modified or unmodified polyvinyl
alcohol, vinyl alcohol-based copolymers such as a saponified
ethylene-vinyl acetate copolymer (hereinafter, abbreviated as
"EVOH") that is a copolymer of vinyl alcohol and ethylene, phenol
resins, epoxy resins, and polysaccharides.
[0036] It is preferred that the polyvinyl alcohol has an average
degree of polymerization of preferably 200 to less than 3000, more
preferably 200 to 3000, and has a degree of saponification of
preferably 95 to 100%, particularly preferably 98 to 99.9%. The
polyvinyl alcohol to be used may be unmodified or modified with
various functional groups.
[0037] An example of such a modified polyvinyl alcohol includes a
polyvinyl alcohol modified with an, anionic, cationic, or nonionic
functional group. An anionic, cationic, or nonionic functional
group can be introduced into a polyvinyl alcohol by a well known
method such as introduction of a monomer having such a functional
group into a polyvinyl alcohol by graft copolymerization, random
copolymerization, or block copolymerization, or treating the end of
a polyvinyl alcohol.
[0038] Examples of the polysaccharides include cellulose,
hydroxyethylcellulose, hydroxymethylcellulose,
carboxymethylcellulose, amylose, amylopectin, starch, oxidized
starch, pullulan, chitin, chitosan, and dextrin.
[0039] These polymers can be used singly or in combination of two
or more of them.
[0040] The organic compound (B) may be any one of an aliphatic
compound, an alicyclic compound, and an araliphatic compound, as
long as it contains a functional group with active hydrogen and/or
a polar functional group with hetero atom.
[0041] The organic compound (B) is preferably a compound containing
at least one selected from the group consisting of a primary amino
group, a secondary amino group, and a carbonyl group which can
interact with a functional group with active hydrogen and/or a
polar functional group with hetero atom contained in the polymer
(A). From the viewpoint of improving gas barrier properties,
urea-based compounds such as urea, dimethyl urea, and thiourea are
particularly preferably used because urea-based compounds are not
sterically-bulky and therefore can fill space between polymer
chains without expanding the space. Among these urea-based
compounds, urea is most preferably used.
[0042] The amount of the organic compound (B) contained in the gas
barrier resin composition is preferably in the range of 2 to 40
parts by weight with respect to 100 parts by weight of the polymer
(A). If the amount of the organic compound (B) contained in the gas
barrier resin composition exceeds 40 parts by weight with respect
to 100 parts by weight of the polymer (A), there is a case where
the organic compound (B) bleeds out from a formed film, thereby
causing blocking. The upper limit of the amount of the organic
compound (B) contained in the gas barrier resin composition is more
preferably 30 parts by weight with respect to 100 parts by weight
of the polymer (A). The lower limit of the amount of the organic
compound (B) contained in the gas barrier resin composition is more
preferably 3 parts by weight, even more preferably 5 parts by
weight, with respect to 100 parts by weight of the polymer (A). By
setting the amount of the organic compound (B) contained in the gas
barrier resin composition to a value within the above range with
respect to 100 parts by weight of the polymer (A), both cohesion
between molecules of the polymer (A) and interaction between the
polymer (A) and the organic compound (B) efficiently occur so that
free volume is reduced, thereby improving gas barrier properties.
In addition, by setting the amount of the organic compound (B)
contained in the gas barrier resin composition to a value within
the above range with respect to 100 parts by weight of the polymer
(A), the gas barrier resin composition can have excellent film
forming properties and a film formed from such a gas barrier resin
composition has high strength.
[0043] As described above, the thus obtained gas barrier resin
composition according to the present invention itself has excellent
film forming properties, and therefore can be formed into a film
usable as it is. However, the gas barrier resin composition
according to the present invention is preferably laminated onto a
base film having high mechanical strength when used.
[0044] Examples of the base film include: polyolefin-based films
such as low-density polyethylene, high-density polyethylene, linear
low-density polyethylene, and polypropylene; polyester-based films
such as polyethylene terephthalate and polybutylene terephthalate;
polyamide-based films such as nylon 6, nylon 66, and
m-xyleneadipamide; polyacrylonitrile-based films; poly(meth)acrylic
films; polystyrene-based films; polycarbonate-based films;
saponified ethylene-vinylacetate copolymer-based films; polyvinyl
alcohol-based films; and laminates of two or more of these films.
The base film may be a non-stretched, uniaxially-stretched, or
biaxially-stretched film. If necessary, the base film may be
subjected to surface treatment (e.g., electric discharge such as
corona discharge or plasma discharge, acid treatment) or
undercoating treatment.
[0045] From the viewpoint of practical use, the thickness of the
base film is preferably in the range of about 1 to 100 .mu.m, more
preferably in the range of about 5 to 50 .mu.m, particularly
preferably in the range of about 10 to 30 .mu.m.
[0046] It is also preferred that the gas barrier film according to
the present invention is further provided with an inorganic layer
laminated on the base film. For example, on at least one surface of
the base film, an inorganic layer such as a metal layer, ametal
oxide layer, or ametal nitride layer may be formed. Such an
inorganic layer can be formed by vapor deposition or sputtering.
Examples of a material for forming the inorganic layer include:
metals such as aluminum, silver, tin, chromium, nickel, and
titanium; metal oxides such as aluminum oxide, magnesium oxide,
titanium oxide, tin oxide, indium oxide alloy, silicon oxide, and
silicon nitride oxide; and metal nitrides such as aluminum nitride,
titanium nitride, and silicon nitride.
[0047] By providing such an inorganic layer, it is possible to
further improve gas barrier properties of the gas barrier film.
Particularly, a metal oxide layer is preferred because gas barrier
properties of the gas barrier film can be improved without loss of
transparency of the gas barrier film.
[0048] The gas barrier resin composition according to the present
invention may be added to a solvent to prepare a coating liquid.
Examples of such a solvent include toluene, xylene, ethyl acetate,
butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl
ketone, tetrahydrofuran, dimethylformamide, dimethylacetamide,
methanol, ethanol, and water. The coating liquid may be either of
an emulsion type or a solution type.
[0049] Examples of a method for preparing such a coating liquid
include a method in which the organic compound (B) is directly
added to a solution or emulsion of the polymer (A) and then they
are stirred, and a method in which the organic compound (B)
previously dissolved or dispersed in water or an organic solvent is
added to a solution or emulsion of the polymer (A) and then they
are stirred.
[0050] The gas barrier resin composition according to the present
invention may contain additives such as thermostabilizers,
antioxidants, reinforcements, pigments, antidegradation agents,
weatherproofing agents, flame retardants, plasticizers, release
agents, and lubricants, as long as the characteristics thereof are
not impaired.
[0051] Examples of the thermostabilizers, antioxidants, and
antidegradation agents include hindered phenols, phosphorous
compounds, hindered amines, sulfur compounds, copper compounds,
alkali metal halides, and mixtures thereof.
[0052] Examples of the reinforcements include clay, talc, calcium
carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium
oxide, calcium silicate, sodium aluminate, sodium aluminosilicate,
magnesium silicate, glass balloon, carbon black, zinc oxide,
zeolite, hydrotalcite, metal fibers, metal whisker, ceramic
whisker, potassium titanate whisker, boron nitride, graphite, glass
fibers, and carbon fibers.
[0053] The gas barrier resin composition according to the present
invention may contain an inorganic layered compound. Preferred
examples of the inorganic layered compound include montmorillonite,
beidellite, saponite, hectorite, sauconite, vermiculite,
fluorinemica, whitemica, palagonite, bronzemica, black mica,
lepidolite, margarite, clintonite, and anandite. Among these
inorganic layered compounds, swollen fluorine mica or
montmorillonite is particularly preferred.
[0054] These inorganic layered compounds may be naturally occurring
or artificially synthesized or modified. Such naturally occurring
or artificially synthesized or modified inorganic layered compounds
may further be treated with an onium salt or the like.
[0055] The thickness of a gas barrier resin film formed from the
gas barrier resin composition is preferably in the range of 0.1 to
5 .mu.m. The lower limit of the gas barrier resin film is more
preferably 0.2 .mu.m, even more preferably 0.3 .mu.m. The upper
limit of the thickness of the gas barrier resin film is more
preferably 3 .mu.m. If the thickness of the gas barrier resin film
is less than 0.1 .mu.m, it is not easy to obtain a uniform gas
barrier resin film and it is difficult to significantly improve gas
barrier properties. In addition, if the thickness of the gas
barrier resin film is less than 0.1 .mu.m, it is difficult to form
such a gas barrier resin film by coating so as not to cause a
defect such as film breakage or crawling. On the other hand, if the
thickness of the gas barrier resin film exceeds 5 .mu.m, there is a
disadvantage that when such a gas barrier resin film is formed by
coating, it is necessary to dry the gas barrier resin film at a
higher temperature for a longer period of time to sufficiently
evaporate a solvent.
[0056] A method for coating a base film with the gas barrier resin
composition is not particularly limited, and can be appropriately
selected according to the kind of base film to be used. Examples of
such a coating method include roller coating, dip coating, bar
coating, die coating, and combinations thereof.
[0057] The coating liquid applied onto a base film is preferably
dried at a temperature of preferably 70.degree. C. or higher, more
preferably 90.degree. C. or higher for preferably 1 second or
longer, more preferably 3 seconds or longer, depending on the kind
of solvent used for preparing the coating liquid. Insufficient
drying may cause deterioration of gas barrier properties.
EXAMPLES
[0058] Hereinbelow, the present invention will be described more
specifically with reference to the following examples. It is to be
noted that in the following examples, the term "part" means "part
by weight" unless otherwise specified.
[0059] (Methods for Evaluating Gas Barrier Properties of Films)
[0060] The gas barrier properties of films of the following
examples and comparative examples were evaluated by measuring
oxygen permeability and water vapor permeability as follows.
[0061] (1) Oxygen Permeability
[0062] The oxygen permeability of each film was measured using an
oxygen permeability measuring device (manufactured by MOCON Inc.
(US) under the trade name of "OXTRAN 2/20") under conditions of
23.degree. C. and 0% RH.
[0063] (2) Water Vapor Permeability
[0064] The water vapor permeability of each film was measured using
a water vapor permeability measuring device (manufactured by MOCON
Inc. (US) under the trade name of "PERMATRAN W3/31") under
conditions of 40.degree. C. and 100% RH.
Example 1
[0065] 439.1 parts of 1,4-bis(isocyanatemethyl)cyclohexane, 35.4
parts of dimethylol propionic acid, 61.5 parts of ethylene glycol,
and 140 parts of acetonitrile as a solvent were mixed, and the
mixture was subjected to reaction at 70.degree. C. in an atmosphere
of nitrogen for 3 hours. The thus obtained carboxylic acid
group-containing polyurethane prepolymer solution was neutralized
at 50.degree. C. with 24.0 parts of triethylamine. 267.9 parts of
the polyurethane prepolymer solution was dispersed in 750 parts of
water with a HOMO DISPER, and then 35.7 parts of
2-[(2-aminoethyl)amino]ethanol was added thereto to carry out a
chain-extending reaction. Acetonitrile was removed by evaporation
to obtain a polyurethane resin water dispersion 1 having a solid
content of 25. wt %. To the thus obtained polyurethane resin water
dispersion 1 (10 parts), 0.5 parts of urea was added, and they were
stirred for 30 minutes to obtain a coating liquid. A 16 .mu.m thick
biaxially-stretched polyethylene terephthalate film whose one
surface had been subjected to corona discharge treatment was
prepared. The coating liquid was applied onto the corona
discharge-treated surface of the polyethylene terephthalate film,
and was then dried at 110.degree. C. for 60 seconds to obtain a
resin layer-coated film having a thickness of 18 .mu.m. The
thickness of the gas barrier resin layer was 2 .mu.m.
Example 2
[0066] 429.1 parts of 1,3-xylylene diisocyanate, 35.4 parts of
dimethylol propionic acid, 61.5 parts of ethylene glycol, and 140
parts of acetonitrile as a solvent were mixed, and the mixture was
subjected to reaction at 70.degree. C. in an atmosphere of nitrogen
for 3 hours. The thus obtained carboxylic acid group-containing
polyurethane prepolymer solution was neutralized at 50.degree. C.
with 24 parts of triethylamine. 267.9 parts of the polyurethane
prepolymer solution was dispersed in 750 parts of water with a HOMO
DISPER, and then 35.7 parts of 2-[(2-aminoethyl) amino]ethanol was
added thereto to carry out a chain-extending reaction. Acetonitrile
was removed by evaporation to obtain a polyurethane resin water
dispersion 2 having a solid content of 25 wt %. To the thus
obtained polyurethane resin water dispersion 2 (10 parts), 0.5
parts of urea was added, and they were stirred for 30 minutes to
obtain a coating liquid. A 16 .mu.m thick biaxially-stretched
polyethylene terephthalate film whose one surface had been
subjected to corona discharge treatment was prepared. The coating
liquid was applied onto the corona discharge-treated surface of the
polyethylene terephthalate film, and was then dried at 110.degree.
C. for 60 seconds to obtain a resin layer-coated film having a
thickness of 18 .mu.m. The thickness of the gas barrier resin layer
was 2 .mu.m.
Comparative Example 1
[0067] A resin layer-coated film was produced in the same manner as
in Example 1 except that addition of urea to the polyurethane resin
water dispersion 1 was omitted.
Comparative Example 2
[0068] A resin layer-coated film was produced in the same manner as
in Example 2 except that addition of urea to the polyurethane resin
water dispersion 2 was omitted.
[0069] The results of the Examples 1 and 2 and Comparative Examples
1 and 2 are shown in Table 1. TABLE-US-00001 TABLE 1 Organic
Compound Polymer (A) (B) Water Vapor Amount of Water Content Oxygen
Permeability Permeability Dispersion Added Polymer Content (part by
(0% RH) (100% RH) Type (part by weight) (part by weight) Type
weight) [cc/m.sup.2 day atm] [g/m.sup.2 day atm] Example 1
Polyurethane 10 2.5 Urea 0.5 25.03 28.24 Resin Water Dispersion 1
Example 2 Polyurethane 10 2.5 Urea 0.5 26.71 29.26 Resin Water
Dispersion 2 Comparative Polyurethane 10 2.5 -- -- 44.59 30.87
Example 1 Resin Water Dispersion 1 Comparative Polyurethane 10 2.5
-- -- 52.97 31.95 Example 2 Resin Water Dispersion 2
[0070] As can be seen from Table 1, the films of Examples 1 and 2
obtained by coating a polyethylene terephthalate film with the
resin composition of the present invention containing a
polyurethane resin and urea had much higher oxygen barrier
properties than the films of Comparative Examples 1 and 2 obtained
by coating a polyethylene terephthalate film with only a
polyurethane resin not containing urea. In addition, the films of
Examples 1 and 2 had higher water vapor barrier properties than the
films of Comparative Examples 1 and 2.
Example 3
[0071] A resin layer-coated film having a thickness of 14 .mu.m was
produced in the same manner as in Example 2 except that the coating
liquid prepared in Example 2 was applied onto an alumina-evaporated
surface of a 12 .mu.m thick alumina-evaporated transparent film
instead of the corona discharge-treated surface of the
biaxially-stretched polyethylene terephthalate film. The thickness
of the gas barrier resin layer was 2 .mu.m.
Example 4
[0072] 1.0 part of urea was added to the polyurethane resin water
dispersion 2 (10 parts) prepared in Example 2, and they were
stirred for 30 minutes to obtain a coating liquid. The thus
obtained coating liquid was applied onto an alumina-evaporated
surface of a 12 .mu.m thick alumina-evaporated transparent film,
and was then dried at 110.degree. C. for 60 seconds to obtain a
resin layer-coated film having a thickness of 14 .mu.m. The
thickness of the gas barrier resin layer was 2 .mu.m.
Example 5
[0073] 0.1 parts of urea was added to the polyurethane resin water
dispersion 2 (10 parts) prepared in Example 2, and they were
stirred for 30 minutes to obtain a coating liquid. The thus
obtained coating liquid was applied onto an alumina-evaporated
surface of a 12 .mu.m thick alumina-evaporated transparent film,
and was then dried at 110.degree. C. for 60 seconds to obtain a
resin layer-coated film having a thickness of 14 .mu.m. The
thickness of the gas barrier resin layer was 2 .mu.m.
Example 6
[0074] 0.2 parts of 1,3-dimethyl urea was added to the polyurethane
resin water dispersion 2 (10 parts) prepared in Example 2, and they
were stirred for 30 minutes to obtain a coating liquid. The thus
obtained coating liquid was applied onto an alumina-evaporated
surface of a 12 .mu.m thick alumina-evaporated transparent film,
andwas then dried at 110.degree. C. for 60 seconds to obtain a
resin layer-coated film having a thickness of 14 .mu.m. The
thickness of the gas barrier resin layer was 2 .mu.m.
Comparative Example 3
[0075] The polyurethane resin water dispersion 2 prepared in
Example 2 was applied onto an alumina-evaporated surface of a 12
.mu.m thick alumina-evaporated transparent film, and was then dried
at 110.degree. C. for 60 seconds to obtain a resin layer-coated
film having a thickness of 14 .mu.m. The thickness of the gas
barrier resin layer was 2 .mu.m.
[0076] The results of the Examples 3 to 6 and the Comparative
Example 3 are shown in Table 2. TABLE-US-00002 TABLE 2 Organic
Compound Polymer (A) (B) Water Vapor Amount of Water Content Oxygen
Permeability Permeability Dispersion Added Polymer Content (part by
(0% RH) (100% RH) Type (part by weight) (part by weight) Type
weight) [cc/m.sup.2 day atm] [g/m.sup.2 day atm] Example 3
Polyurethane 10 2.5 Urea 0.5 0.14 0.83 Resin Water Dispersion 2
Example 4 Polyurethane 10 2.5 Urea 1.0 0.36 0.88 Resin Water
Dispersion 2 Example 5 Polyurethane 10 2.5 Urea 0.1 0.64 0.99 Resin
Water Dispersion 2 Example 6 Polyurethane 10 2.5 Dimethyl 0.2 0.59
0.90 Resin Water Urea Dispersion 2 Comparative Polyurethane 10 2.5
-- -- 0.76 1.04 Example 3 Resin Water Dispersion 2
[0077] As can be seen from Table 2, the films of Examples 3 to 6
obtained by coating an alumina-evaporated surface of an
alumina-evaporated transparent film with the resin composition of
the present invention had higher oxygen barrier properties and
water vapor barrier properties than the film of Comparative Example
3.
Example 7
[0078] 7.5 parts of an aromatic polyurethane-based aqueous adhesive
for dry laminate (manufactured by Dainippon Ink and Chemicals,
Incorporated under the trade name of "DICDRY WS-325"), 1 part of a
curing agent (manufactured by Dainippon Ink and Chemicals,
Incorporated under the trade name of "LJ-55"), and 15 parts of
purified water were mixed, and the mixture was stirred for 30
minutes to obtain an adhesive for dry laminate 1. To the thus
obtained adhesive for dry laminate 1 (10 parts), 0.5 parts of urea
was added, and they were stirred for 30 minutes to obtain a coating
liquid. A 16 .mu.m thick biaxially-stretched polyethylene
terephthalate film whose one surface had been subjected to corona
discharge treatment was prepared. The coating liquid was applied
onto the corona discharge-treated surface of the polyethylene
terephthalate film, and was then dried at 110.degree. C. for 30
seconds to obtain a resin layer-coated film having a thickness of
18.4 .mu.m. The thickness of the gas barrier resin layer was 2.4
.mu.m. The thus obtained resin layer-coated film was laminated onto
a 25 .mu.m thick unstretched polypropylene film by dry lamination,
and was then aged at 40.degree. C. for 2 days to obtain a gas
barrier laminated film 1.
Example 8
[0079] 7.5 parts of an aromatic polyurethane-based alcohol soluble
adhesive for dry laminate (manufactured by Dainippon Ink and
Chemicals, Incorporated under the trade name of "DICDRY AS-106A"),
0.75 parts of a curing agent (manufactured by Dainippon Ink and
Chemicals, Incorporated under the trade name of "AK-50"), and 12.4
parts of methanol were mixed, and the mixture was stirred for 30
minutes to obtain an adhesive for dry laminate 2. 0.5 parts of urea
was added to the adhesive for dry laminate 2 (10 parts), and they
were stirred for 30 minutes to obtain a coating liquid. A 16 pn
thick biaxially-stretched polyethylene terephthalate film whose one
surface had been subjected to corona discharge treatment was
prepared. The coating liquid was applied onto the corona
discharge-treated surface of the polyethylene terephthalate film,
and was then dried at 110.degree. C. for 30 seconds to obtain a
resin layer-coated film having a thickness of 18.4 .mu.m. The
thickness of the gas barrier resin layer was 2.4 .mu.m. The thus
obtained resin layer-coated film was laminated onto a 25 .mu.m
thick unstretched polypropylene film by dry lamination, and was
then aged at 40.degree. C. for 2 days to obtain a gas barrier
laminated film 2.
Comparative Example 4
[0080] A laminated film 3 was produced in the same manner as in
Example 7 except that addition of urea was omitted.
Comparative Example 5
[0081] A laminated film 4 was produced in the same manner as in
Example 8 except that addition of urea was omitted.
[0082] The results of the Examples 7 and 8 and Comparative Examples
4 and 5 are shown in Table 3. TABLE-US-00003 TABLE 3 Organic
Compound Polymer (A) (B) Water Vapor Amount of Water Content Oxygen
Permeability Permeability Dispersion Added Polymer Content (part by
(0% RH) (100% RH) Type (part by weight) (part by weight) Type
weight) [cc/m.sup.2 day atm] [g/m.sup.2 day atm] Example 7 Adhesive
for Dry 10 1.7 Urea 0.5 90.37 8.71 Laminate 1 Example 8 Adhesive
for Dry 10 1.7 Urea 0.5 90.82 8.70 Laminate 2 Comparative Adhesive
for Dry 10 2.0 -- -- 98.04 8.95 Example 4 Laminate 1 Comparative
Adhesive for Dry 10 2.0 -- -- 98.82 8.91 Example 5 Laminate 2
[0083] As can be seen from Table 3, the laminated films of Examples
7 and 8 obtained by dry lamination using the resin composition of
the present invention containing a urethane-based adhesive for dry
laminate and urea exhibited higher gas barrier properties than the
conventional laminated films of Comparative Examples 4 and 5. From
the result, it has been found that the resin composition of the
present invention is very useful for forming a laminated film
composed of a gas barrier film and a sealant film.
Example 9
[0084] 5.0 parts of an epoxy resin with glycidyl amine moieties
derived from m-xylylenediamine ("MT-9312 (base resin)" manufactured
by MITSUBISHI GAS CHEMICAL COMPANY, Incorporated) and 15.9 parts of
a methanol solution of an epoxy resin curing agent derived from
m-xylylenediamine and methyl acrylate (solid concentration: 65%,
"MT-9312 (curing agent)" manufactured by MITSUBISHI GAS CHEMICAL
COMPANY, Incorporated) were added to a mixed solvent of 41.0 parts
of methanol and 5.0 parts of ethyl acetate, and they were stirred
for 30 minutes to obtain an epoxy-based resin solution 1 having a
solid content of 25 wt %. To the epoxy-based resin solution 1 (10
parts), 0.2 parts of urea was added, and they were stirred for 30
minutes to obtain a coating liquid. The thus obtained coating
liquid was applied onto an alumina-evaporated surface of a 12 .mu.m
thick alumina-evaporated transparent film, and was then dried at
110.degree. C. for 60 seconds to obtain a resin layer-coated film
having a thickness of 14 .mu.m. The thickness of the gas barrier
resin layer was 2 .mu.m.
Comparative Example 6
[0085] A resin layer-coated film was produced in the same manner as
in Example 9 except that addition of urea to the epoxy-based resin
solution 1 was omitted.
[0086] The results of Example 9 and Comparative Example 6 are shown
in Table 4. TABLE-US-00004 TABLE 4 Organic Compound Polymer (A) (B)
Water Vapor Amount of Water Content Oxygen Permeability
Permeability Dispersion Added Polymer Content (part by (0% RH)
(100% RH) Type (part by weight) (part by weight) Type weight)
[cc/m.sup.2 day atm] [g/m.sup.2 day atm] Example 9 Epoxy-Based
Resin 10 2.5 Urea 0.2 0.49 0.91 Solution 1 Comparative Epoxy-Based
Resin 10 2.5 -- -- 0.64 1.01 Example 6 Solution 1
[0087] As can be seen from Table 4, the film of Example 9 obtained
by coating an alumina-evaporated surface of an alumina-evaporated
film with the resin composition of the present invention containing
an epoxy-based resin and urea had higher oxygen and water vapor
barrier properties than the film of Comparative Example 6 obtained
by coating an alumina-evaporated surface of an alumina-evaporated
film with only an epoxy-based resin.
INDUSTRIAL APPLICABILITY
[0088] The present invention can be applied to various gas barrier
films for packaging such as gas barrier resin films for food
packaging. However, applications of the present invention are not
limited to such gas barrier films.
* * * * *